Finally got around to playing this, and you did an awesome job!! I love the music and the sprite work is impeccable. It felt a bit weird to play a Megaman game that doesn't have limited lives, honestly, but I died a good chunk of times so it's not unappreciated.
Some stuff I took note of while playing:
1: For some reason, the main menu theme doesn't loop. Also there's a typo in the options menu - "resart" instead of "restart". Little things to fix!
2: Some control issues - the camera reacts a bit too early, I feel like it'd be better if it only turned when you were near the middle. As is, it can get a bit disorienting if you turn around to shoot something and the camera shifts half a screen. As well, the jump feels a little heavy? I think it's because you don't normally spend enough time at the height of your jump, because I noted that when in space or lightly bonking your head, it feels a lot nicer.
3: I did the levels out of order, so I tried using the fire weapon on Deadeye-rate since he had the plant stage - it didn't work, but turns out Deadeye has a rather bad bug. If you run right up to him while he's trying to back off and shoot, he tries to back through the wall and gets stuck against it. First time it happened I backed up to free him but then he killed me, so second round I just trapped and shot him to death. It felt a bit mean. (Vaguely related, why do the gun enemies in Botanical Garden not fall over upon shooting like all the other ones?)
4: The sound effect for a shield deflecting my bullet is a lot more satisfying than the sounds for hitting or killing an enemy. The hitting sound is just so dull and muted in comparison...
Sorry if these issues seem nitpicky - but everything else is so good, I have nothing else to remark on! It truly does feel like a real, full game and I'm incredibly impressed you managed to make this whole thing in just 10 days! Top scores from me, I look forward to playing the full release!!